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Infarct size reduction by AT1-receptor blockade through a signal cascade of AT2-receptor activation, bradykinin and prostaglandins in pigs.

Abstract：

OBJECTIVE:We studied the effect of the angiotensin II type 1 (AT1)-receptor antagonist candesartan on infarct size resulting from regional myocardial ischemia in pigs. BACKGROUND:The effects of AT1-receptor blockade on infarct size in different species remain controversial and its potential cardioprotective mechanisms are still unclear. In pigs, infarct development closely resembles that observed in humans. METHODS:A total of 62 enflurane-anesthetized pigs underwent a protocol of 90-min low-flow ischemia and 120-min reperfusion. Systemic hemodynamics (micromanometer), regional myocardial function (sonomicrometry), regional myocardial blood flow (microspheres) and infarct size (TTC [triphenyl tetrazolium chloride]-staining) were determined. RESULTS:Left ventricular peak pressure decreased with candesartan (1 mg/kg i.v.) from 97+/-2 standard error of the mean (SEM) to 86+/-5 mm Hg and was then readjusted by aortic banding. In placebo pigs (n=9), infarct size was 21.8+/-4.8% of the area at risk. Candesartan (n=7) reduced infarct size to 9.7+/-2.5% (p < 0.05). Pretreatment with the AT2-receptor antagonist PD123319 (3 microg/kg/min intracoronarily [i.c.]; n=8), the bradykinin B2-receptor antagonist HOE140 (0.01 microg/kg/min i.c.; n=8) or the cyclooxygenase inhibitor indomethacin (10 mg/kg i.v.; n= 8) per se did not affect infarct size but did abolish the reduction of infarct size achieved by candesartan (PD123319 + candesartan (n=7): 23.2+/-4.7%; HOE140 + candesartan (n=7): 18.2+/-4.0%; indomethacin + candesartan (n=8): 21.1+/-5.2%). Hemodynamics, regional myocardial blood flow during ischemia and the area at risk were comparable among all groups of pigs. CONCLUSIONS:Reduction of infarct size by the AT1-receptor antagonist candesartan in pigs involves angiotensin II type 2 receptor (AT2) activation, bradykinin and prostaglandins.

journal_name

J Am Coll Cardiol

journal_title

Journal of the American College of Cardiology

authors

Jalowy A,Schulz R,Dörge H,Behrends M,Heusch G

doi

10.1016/s0735-1097(98)00441-0

subject

Has Abstract

pub_date

1998-11-15 00:00:00

pages

1787-96

issue

eissn

0735-1097

issn

1558-3597

pii

S0735-1097(98)00441-0

journal_volume

pub_type

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Infarct size reduction by AT1-receptor blockade through a signal cascade of AT2-receptor activation, bradykinin and prostaglandins in pigs.